[4] +der Lichtäther+: luminiferous ether. [5] +daran ... dass+: by the fact that; _lit._ by this, namely that ..., +Daran+ represents the following clause and anticipates it. [6] +Besitzen+; see 1 Note 2. [7] +der Kernschatten+: umbra; +der Kern+, kernel. [8] +der Halbschatten+: penumbra. [9] +unmittelbar+: directly. [10] +auf ... angewiesen+: confined to. [11] +der Einfallswinkel+: angle of incidence. [12] +der Schirm+: screen. 22. [1] +der ebene Spiegel+: plane mirror. [2] +das Spiegelbild+: reflected image. [3] +der Senkrechte+: the vertical, perpendicular; see 1 Note 10. [4] +einem ... Kreis+: a circle. [5] +der Durchschnitt+: section. [6] +Perlen+: beads. [7] +beim Hineinblicken+: on looking in. [8] +ein ... Mittel+: a medium. [9] +zwei ... Ebenen+: two planes. This sentence is an example of one compound adjective construction within another. [10] +brechend+: refracting. [11] +einen ... Spalt+: a slit. [12] +bandförmig auseinandergezogen+: drawn out in the form of a ribbon. [13] +brechbar+: refrangible. [14] +einzelne+: single, separate, individual. [15] +derartig+: that kind, such. [16] +indem man+; see 1 Note 9. [17] +das Knallgebläse+: oxy-hydrogen blowpipe. [18] +die betreffenden Metalle+: the metals in question. [19] +geschlossen werden kann+: conclusions may be drawn. 23. [1] +vermittelt+: transmitted. [2] +schrieb ... zu (zuschreiben)+: ascribed, attributed. [3] +und zwar+: and moreover. [4] +nimmt ... zu ... ab (zunehmen, abnehmen)+; increases, decreases. [5] see 1 Note 9. [6] +die Lagenänderung+: change of position. [7] +bei+; see 13 Note 12. [8] +der Abstand+: distance apart. 24. [1] +um+: to the extent of, by. [2] +bezw. (beziehungsweise)+; see 2 Note 10. [3] +der Träger+: beam, girder. [4] +das Mauerwerk+: masonry. [5] +der Radreifen+: tire of a wheel. [6] +gilt (gelten)+: holds true. [7] +der Schrumpfring+: hoop shrunk on a gun. [8] +bei+; see 13 Note 12. [9] +übt ... aus (ausüben)+: exerts. [10] +die Dampfspannung, die Spannkraft+: tension. [11] +es bilden sich+: there are formed. [12] +Verdampfen+: vaporization. [13] +Verdunsten+: evaporation (without artifical heat.) 25. [1] +bei+; see 13 Note 12. [2] +die Vakuumpfanne+: vacuum pan. [3] +die Zuckersiederei+: sugar refinery; +sieden+, to boil. [4] +umgekehrt+: conversely. [5] +der Papinsche Topf+: Papin's digestor. [6] +das Sicherheitsventil+: safety-valve. [7] +die Spannkraft+: the tension. [8] See 1 Note 9. [9] +absperren+: to bar off = to confine. [10] +noch so gross+: never so great, no matter how great. [11] +tropfbar+: capable of forming drops. [12] See 18 Note 6. [13] +der Grenzwert+: limit of value; limit. 26. [1] +einen beliebig grossen Zwischenraum+: a distance as great as may be desired = any distance. [2] +die Strahlung+: radiation. [3] +die Leitung+: conduction. [4] +gleicht sich ... aus (sich ausgleichen)+: equalizes itself. [5] +wir haben uns ... vorzustellen+: we must conceive.